Such analytical devices are applied, for example, in process measurements technology or in industrial measurements technology. For example, analytical devices can serve for monitoring and optimizing the cleaning effectiveness of a clarification plant, in monitoring the activation basin and the clarification plant outlet or in the case of the control of additive metering. Furthermore, analytical devices can be applied for monitoring drinking water or for quality monitoring of food. Measured and monitored are, for example, the content of a sample as regards special substances, for example, ions such as ammonium, phosphate or nitrate, or biological or biochemical compounds, e.g. hormones, and even microorganisms.
Frequently in analytical devices, one or more reagents are added to the sample to be analyzed, so that a chemical reaction occurs in the liquid sample. Preferably, the reagents are so selected that the chemical reaction can be followed by means of physical methods, for example, by optical measurements. For example, the chemical reaction can effect a color change, which is detectable photometrically, thus with optical means.
In order to use such analytical methods in an automated manner, for example, in industrial applications, it is necessary to provide an analytical device, which performs the required analytical method in an automated manner. The most important requirements for such an analytical device are, besides sufficient accuracy of measurement, robustness, simple serviceability and the assurance of a sufficient working, and environmental, safety. Since the reagents used for analysis are sometimes not dischargeable into the water system, their safe disposal plays likewise an essential role.
From the state of the art, there are already semiautomatic and automatic analytical devices known. These are often relatively complicated in construction and, consequently, susceptible to malfunctions, and, as a rule, only serviceable by trained technicians. Thus, for example, DE 102 22 822 A1 and DE 102 20 829 A1 disclose online analyzers for analyzing measurement samples. The online analyzers are, in each case, embodied as cabinet devices, in which are arranged a control unit, reagent supply containers, pumps for conveying and dosing, or metering, reagents into a mixing cuvette for mixing the reagents with the liquid, a waste container, as well as an optical unit for optical measurements on the liquid sample treated with reagents in the mixing cuvette. The reagents are supplied via hose linkages from the reagent containers into the mixing cuvette. Correspondingly, used liquid is transferred from the mixing cuvette, in turn, via a hose linkage into the waste container. If the waste container or one or more of the reagent supply containers must be replaced, attention must be paid that the hose linkages are then correctly reconnected. The hoses and the supply pumps are susceptible to material fatigue and must likewise be subjected to maintenance or replaced from time to time.